Russian servicemen walk near a military build-up in the town of Klintsy in Bryansk region, Russia, June 6, 2016. Photo: Reuters/Anton Zverev

Russia is building an army base near its border with Ukraine, the latest in a chain of new military sites along what the Kremlin sees as its frontline in a growing confrontation with NATO.

While there have been no clashes between the former Cold War rivals, Russia is building up forces on its western frontiers at a time when the NATO alliance is staging major military exercises and increasing deployments on its eastern flank.

A Reuters reporter who visited the Russian town of Klintsy, about 50 km (30 miles) from Ukraine, saw a makeshift army camp, large numbers of newly-arrived servicemen and military vehicles.

Two soldiers in camouflage gear who were manning a checkpoint in a forest turned the reporter away, saying they were guarding a "special military site".

Last year, Reuters also reported on construction of two other bases further to the south on Russia's border with Ukraine.

The defense ministry has not acknowledged the deployment of troops to Klintsy, which usually serves as a stop for truck drivers traveling between Russia, Ukraine and Belarus.

However, a town council official said Klintsy had been chosen as the site of a newly-formed division, and that so far about 240 soldiers had arrived. "What's to hide? That they've come? They've arrived," said council deputy chairman Oleg Kletny. "They're going to be garrisoned here."

When completed, the base will be the latest component in a build-up of forces along a line running from the Baltic Sea in the north to the Black Sea in the south.

On the western side of the line, NATO has been rotating troops and equipment in greater numbers to members states that were part of the Soviet-led Warsaw Pact during the Cold War.

The Western alliance, which says it's responding to Russian military intervention in Ukraine, was this week staging one of its biggest exercises in eastern Europe since the end of the Cold War.

To the east, Russia is building up its own forces, saying it needs to protect itself from NATO's eastward advance.

Each side says it is only responding to steps taken by the other, but the build-up risks locking NATO and Russia into a spiral of measure and counter-measure from which it will be difficult to escape.

Russia and NATO member states share borders around the Baltic Sea, while further south the two blocs are separated by Ukraine and Belarus.

But since Ukraine's pro-Moscow president was ousted in a popular uprising two years ago and replaced with a Western-leaning administration, the perception in Moscow is that Ukraine has become, de facto, a NATO satellite.

Anti-tank defenses

Russia has pulled out of the treaty on Conventional Forces in Europe, a post-Cold War pact that limits the deployment of troops in Europe, so it is free to move extra troops and hardware to its western border.

On Monday Klintsy, normally a sleepy town, was a hive of military activity. The Reuters reporter saw about a dozen tents and the same number of military vehicles in a temporary camp in a clearing in a forest where the troops will be billeted until their permanent base is ready.

Military trucks drove through the town, which lies in an area that is the closest point on Russian territory to the Ukrainian capital, Kiev, 280 km away.

About a dozen servicemen were at a gas station near the camp, buying food supplies. A road near the camp was blocked off by antitank obstacles and road spikes.

Last week, Russia's Interfax news agency quoted an unnamed source familiar with the deployment to Klintsy as saying it "can be seen as a response to the growing activity of the North Atlantic Alliance near Russia's borders".

The defense ministry did not reply to questions from Reuters about the base and its purpose.

Council deputy chairman Kletny said the troops, from a motorized infantry division, started arriving on May 30. They came from a base in Yekaterinburg, in the Ural mountains region about 2,000 km to the east of Klintsy.

He said they were deployed following a decision earlier this year by Defence Minister Sergei Shoigu to create three new divisions. The soldiers will be eventually garrisoned in the grounds of a disused military base in Klintsy which they are renovating, said Kletny.

"It's good that the military will come; our demographic situation will improve, we'll get a bigger population. If servicemen come her with their families, that will be good too," he told Reuters.

A notice lodged with Klintsy town council and seen by Reuters stated that approval is being sought for re-zoning and construction works on two plots of land with a total area of 142 hectares (351 acres), or about the size of 140 soccer pitches.

The plots of land would be used "for the interests of the Russian armed forces", according to the notice.